Shotgun choke



NOV. 16, 1948. EGLESQN 2,453,747

- SHOTGUN CHOKE Filed on. 31, 1947 2 Sheets-Shet 1 IQTTUPA Z'VS Nov. 16,1948. E, A, EGLESON 2,453,747

SHOTGUN CHOKE Filed 001;. 31, 1947 2 Sheets-Sheet 2 IIVVENTOR; WdlW BYPatented Nov. 16, 1948 i Sim 1 l This invention relates to gun chokes.

The general object of the invention is to provide a new and improved gunchoke for shotguns arranged to be operated by the force of the expandinggases of combustion oi the powder to. effect automatically 9. chokingaction upon the muzzle of the gun so that, one shell having been fired,the muzzle will have been constricted tor the purpose of concentratingthe shot pattern upon the firing of another shell.

A special object of the invention is to provide such a gun choke whichmay be attached to the muzzle of a shotgun barrel and may be manuallyadjusted so as to provide. an unchoked effective muzzle, and at the sametime is operable so that upon the firing of a. shell the force'of theexpanding gases of combustion of the powder will operate to effect apredetermined choking action upon the effective muzzle. Further, theinvention contemplates such a gun choke which, attached to the muzzle ofa shotgun, may be manually adjusted to choke the effective muzzle in aselected degree, and in which, upon the firing of a shell, the gases maybe utilized to effect an additional, and predetermined, choking actionupon the effective muzzle.

Another object is to provide apparatus which may be attached to amanuallymperable gun choke, said apparatus being arranged to be operatedby the force of the expanding gases of combustion of the powder toeffect choking action of the gun choke.-

Another object is to provide means whereby the force of the expandinggases of combustion of the powder of a fired shotgun shell may beutilized to effect a rotary motion of a rotatable member of a gun chokerelatively to a split muzzle extension so as to constrict the elementsof the split muzzle extension, and thereby vary the orifice throughwhich the shot emerge.

Also, in general, the invention contemplates an improved automatic gunchoke arranged to be operated by the force of the expanding gases ofcombustion of the powder of a fired shotgun shell so as to effect a.construction of the muzzle of the .gun immediately following theemergence of the .shot from each of a plurality of fired shells, so thatthe shot patterns of the fired shells successively decrease in diameter;and so that, in rapid firing, as, for example, in shooting at awithdrawing target, the pattern diameter decreases automatically asshells are fired, thereby compensating for the increasing distancebetween the muzzle and the target.v Further, the inventioncontemplatesthe provision ofmeanswhereby the 14 Claims. (Cl. 42- 79)delay incident to manual choking-tot themuzzle may be avoided in rapid.firing of ashotgun.

These and other objects willbe more-fully -understood from the followingdescription and from thedrawings in which I I Fig. 1 is a sideview of agun choke embodying the invention; r

. Fig. 2 is a section taken approximately onthe line 22 of Fig. 1;

Fig. 3 is a front view of the gun choke of Fig.- i; Fig. ,4 is a sectiontaken on the line 4-4 ofFig.

FigsQS and 6 are details of means provided on the gunchoke of Fig. 1 forpredetermining the v degree of choke to be automatically eflfected;

Fig. 7 is an axial section similar to Fig. 2 but on a slightly largerscale of a modified embodiment of the invention; and 1 Fig. sis an axialsection similar to Fig. '7 0! another modification of the invention. A

The embodiment ofthe invention illustrated in (Figs. 1 to 6, inclusive,is a complete automatic gun choke arranged to be applied to the muzzleof a shotgun; r

Figs. 1 and 2 show the forward end of a shotgun barrel I. In- Fig. 2 theactual muzzle of the barrel is designated as 2. l The outside of themuzzle end of the barrel is threaded, and the sleeve 3 is internallythreaded at 4 for engaging the threaded end of the barrel I so thatitmay be attached to the muzzle end of the gun barrel. A split muzzleextension 3a of the gun barrel has its forward end tapered externally at5, the tapered portion being split, parallel to the axis of the sleeve,by a plurality of slots 6 to provide a plurality of oonstrictable.fingers I (see also Fig. 4). The muzzle extension 311. is shown as aseparate member with its rearward end externally threaded for engagementwith the internal threads of the portion of the sleeve 3 that extendsbeyond the muzzle 2 for holding the gun barrel muzzle and muzzleextension in a butting relation as shown.

internally machined, The sleeve 3' is externally threaded at 8; andmounted thereon is a second sleeve 9, having internal threads at itsrear end so that it may be adjustably positioned upon sleeve 3. Thesleeve!) is internally tapered and constricted toward its forward end toformra conical cam III which operates to constrict the fingers Iaccordingly as the sleeve 9 is progressively threaded upon sleeve 3 Thesleeve '9 is seen to be an annular member that is internally threadedfor rotation relative to the split muzzle assays? 3 extension to andthat is arranged to constrict the split muzzle extension when rotated.

The forward -end of sleeve 9 is externally threaded at I I and mountedthereon is the annular chamber member I! having internal threads at itsrear end whereby it may betightly fitted upon the sleeve 9 so as to formwhat is in eifect an integral projection of the sleeve! extending beyondthe mouth of the mumle extension la. Boththe inside and outside of thechamber member I! are constricted abruptly near the forward end to formthe exit tube It, the internal diameter of which provides proximateclearance for the shot pattern when the split muzzle extension isunconstricted. Preferably, the internal diameter of the exit tube I9 isapproximately equal to the internal diameter of the unchoked muzzlewhile being slightly greater in diameter so that the widest shot patternwill clear without interference. For example, if the internal diameterof the unchoked muzzle is .730 inch plus or minus .005 inch, theinternal diameter of the exit tube I! may advantageously be .775 inch.The lntemal diameter of the intermediate portion of the chamber memberI! is greater than the internal diameter of the exit tube l9 so that achamber I4 is provided rearward of exit tube. The cylindrical wall ofthe chamber member i2 is provided with a plurality of angularly spacedlongitudinally extending slots i5. Each such slot passes through thewall, not radially, but at an angle, as shown in Fig. 4, therebyell'ectlvely converting the remaining and intervening strips ii of thewall into vanes having deflecting surfaces adapted to impart torque tothe chamber member tending to rotate it in a clockwise direction (Fig.4) under the influence of expanding gas passing outwardly through theslots IS. A plurality of relatively small, angularly spaced holes I! areprovided in the shoulder of chamber member I: which is 4 v v lng. whenthe crosshead has been dropped into any of the slots I! it is apparentthat the sleeve 9 cannot be advanced upon sleeve. 9 more than thatdistance corresponding to the rotary motion of sleeve 9 suiiicient tobring the lug 2| into contact with the crosshead of key 29. as shown inFigs. 1 and 5. The key :0, therefore, can be utilized as a stop toarrest the rotary motion of the sleeve 9 at a predetermined positionwhich is controlled depending upon the indexing slot in which thecrosshead of the key 29 is inserted. Whichever indexing slot thecrosshead of the key so is inserted in. the sleeve 9 may be manuallyrotated in counterclockwise direction nearly one full turn (380) to theposition shown in Fig. 6. The pitch of the threads 9 relative to cam i9is preferably proportioned so that counterclockwise rotation of sleeve 9through the full extent permitted by the key 29 will permit in all casesthe lingers of the muzzle extension to to assume their fullyuneonstricted (improved cylinder) position relative to the gun. Theremay be any desired number of the index slots i9, as for example, sevenas shown. It the crosshead of the key 20 is positioncd in the slothaving the index number I, the key 29 may be used as a chock so as toprevent clockwise rotation of the sleeve 9 to effect any choking action.At the other extreme. when the crosshead of the key 20 is inserted inthe slot indexed as number I, then the sleeve 9 can be rotated toconstrict the muzzle extension to the full choke position. When thecrosshead is in-- serted in any of the intermediate indexing slots, therotation of the sleeve can be arrested at any intermediate choke as maybe desired. When the key 20 is in any of the slots other than thatnumbered I, the sleeve 9 can be manually rotated clo kwise until the lug2| contacts the crosshead of the key-29. Any degree of choke asdetermined a by the position of the key can be effected in this formedwhere this member is abruptly constricted near the forward end to formthe exit tube i9, said holes communicating from the inside of chamber idto the exterior of the chamber member i2 and preferably having theiraxes. inclined as shown so as to impart torque to the chamber member 12in the same direction (clockwise) as that imparted by the slots I! whenthe gun is fired. (See Figs. 2 and 3.)

On the rearward end of-the sleeve 9 there is proyided a shoulder l8having on its forwardly disposed edge a series of angularly spaced slotsf9. which are shown in Figs. 1, 5 and 6 to be indexed with indexingnumerals. On the sleeve 9, forward of the shoulder I8, is a key 20formed of a 'r-shaped strip of suitable mater! ll, preferably hard,resilient metal, curved flatwise to form a nearly complete hoop thatslidably engages the sleeve 3. The crosshead of the T is shaped to bereceived on one side within any of the slots l9, and on the other sideto be engaged by and to serve as a detent for a lug 2| provided on therear end of sleeve 9. In order to permit adjustment or disassembly ofthe gun choke, the sleeve 9 may be rotated counterclockwise upon sleeve9 until the crosshead of the key 20 can be moved into the slot 22 thatis in the sleeve 9 alongside the lug 2| so that the crosshead will beout of contact with any of the slots l9 as shown in dotted lines in Fig.6. With the crosshead of the key 29' moved to this position, the key maybe rotated with the sleeve 9 around sleeve 3 until the crosshead isbrought opposite any of the indexing slots l9, or, if desired, thesleeve 9 can be completely removed for disassembly and cleanway andfiring of the gun will not effect any further choking action. However,if the sleeve 9 is rotated counterclockwise from any such position, thesleeve will be free to be rotated clockwise automatically upon firing ofthe gun until the rotary motion of the sleeve is arrested by theposition of the keylll, and this action automatically constricts themuzzle extension 3a to a more fully choked position. The gun can, ofcourse, then be immediately fired again with the choke in the moreadvanced position.

When the position of the sleeve 9 relative to the key 20 is such thatadvancing rotary motion may be assumed by the sleeve, the rotation ofthe sleeve 9 upon the firing of the gun to choke the muzzle extension 3ais caused by the expansion of the gases following the wedding and shotas they are discharged from the muzzle extension through the chambermember l2 and through the exit tube Id. The gases following the waddingand shot, of course, expand rapidly and escape through slots I! in thechamber II. This action is augmented by the momentary blocking of otheravenues of escape as the wedding and shot pass through the exit tube l3.The rapidly expanding gases which violently escape through the slots l5impart moments against the deflecting faces of the strips l6 that rotatethe chambermember I2 and in turn the sleeve 9) in a clockwise direction.During the occurrence of this action, the gases escaping through theholes II impart a rearward reaction upon the chamber member l2 and uponthe sleeve 9 that assists in eflecting the choking action effected bythe rotation of the sleeve 9. When the holes I! likewise are formed (asshown) so that their axes are not parallel to the bore of the barrel,but at an angle, the gas which escapes through them imparts, in additionto a rearward moment,

' with theiraxes parallel to the bore of the barrel while stillaffording adequate torque to effect/the automatic choking action whenthe gun is fired. Whether the holes II have their axes parallel'to thebarrel or at an angle thereto, they are regarded as longitudinallyextending orifices.

Depending upon the friction and inertia of the parts of the chokemechanism, the torque impulse upon the. chamber member I2 is sufiicientto effect a full rotation of the sleeve 3 or only a fractional portionof a full revolution. For example, the

3 impulse imparted by the firing of the gun may be sufiicient to rotatethe sleeve 9 through a half revolution, more or less. In such case, ifthe key is set in the full choke position and the sleeve is initiallymanually retracted to the unchoked (improved cylinder) position, thefirst shot will rotate the sleeve 9 to effect approximately half choke(modified choke), while the second shot will cause further rotation ofthe sleeve 3 to effect full choke, at which time a third shot may thenbe fired. In order to assist in the, manual setting of cylinder 3 at theimproved cylinder position or at any intermediate setting, the lug 2|may be used as an indexing indicia relative to the indexing slots 19,although any other indexing indicia may be used as may be convenient.

In Fig. '7 another embodiment is shown which illustrates the applicationof this invention to the automatic operation of a gun choke adapted tobe detachably secured to the muzzle of a shotgun. In this modification,the split muzzle extension is detachably secured to the gun barrel I asby the threaded engagementshown. The muzzle of the gun barrel isindicated at 2. The split muzzle extension 30 has constrictable fingers3| and external tapers at 32 and 32a. The sleeve 33 provides the camsurfaces acting on the external tapers 32 and 32a for progressivelyconstricting the fingers 3| when the sleeve 33 is rotated under theinfluence of the threading 29. The device thus far described is adaptedfor use as a manually operated choke. According to this invention, thechoke is made automatically operable by the attachment to the sleeve 33of the chamber member 34 as by the threaded engagement 35.

The chamber member 34 corresponds to the chamber member l2 shown inFigs. 1 to 6 and the slots 15, the vane-like wall strips IS, the holesl1 and the exit tube l3 correspond to the like-numbered elements ofchamber member l2. The action of the vanes in the chamber member 34 ineffecting rotary motion of the chamber and sleeve 33 to effect anautomatic choking of the split muzzle extension when the gun is fired issimilar to that previously described in connection with the embodimentshown in Figs. '1 to 6. In this embodiment there is no stop means forarresting the rotation of thesleeve 33 and reliance is placedon thefriction and inertia of the rotatable parts, as, for example, so thatthe torque impulse tending to rotate the sleeve 33 upon the firing ofthe gun will afford half of a complete rotation, more or less, of thesleeve. However, if desired, a stop mechanism may be employed, as, forexample, a stop mechanism such as that shown for purposes of lllustration in Figs. 1 to 6. However, it is not essential to employ a stopdevice, and in certain cases omission of the stop mechanism may beadvantageous and 33.

in permitting successively increased choke increments upon successiveshots fired. Of course, conventional indexing indicia may be employed toindicate therelative positions of the sleeve 33 In Fig. 8, anotherembodiment of this invention is shown wherein the split muzzle extensionis an integral part of the muzzle end of the shotgun barrel. The muzzleextension comprises the constrictable fingers 36 which areexternallytapered,

the taper being indicated at 31. The sleeve 39 by the threads 38 isrotatably secured to the gun barrel just back of the inner ends of thefingers 36 so that by rotation of the sleeve 39 the internal taper ofthe outer end of sleeve 39 will act to choke the muzzle of the gunbarrel. The chamber member 40 is similar to the chamber member 139i theembodiment shown in Figs. 1 to 6 including'the slots IS, the vanes IS,the holes I! and the exit tube l3. As in the case of the embodimentshown in Fig. '7, a stop device to arrest the rotation of the sleeve 33may be employed if desired and appropriate indexing indicia may beemployed.

While this invention has been described in connection with the specificembodiments shown, it is apparent that the principles of this inventionpermit other modifications. Thus, the slots in the chamber member may beof other configurations as by making them spiral or of other lengths,and it is apparent that any openings laterally adjacent the mouth of thesplit muzzle extension can be employed which provide deflecting surfacesfor imparting torque to the sleeve for choking the split muzzleextension of the gun barrel. The holes I! are not essential and may beomitted. The exit tube l3 may also be omitted but augments the torque.When the exit tube I3 is employed and is preferably about inch inlength, the torque action has been found to be most efiective. Moregenerally, the scope of the invention whereby a shotgun choke isautomatically operated by utilizing the expanding gases discharged fromthe shotgun barrel to supply torque for rotating a number to constrictthe choke is to be governed by the language of the following claims.

' rotatable sleeve member therefor constructed and arranged to constrictsaid split muzzle extension upon rotation thereof relatively to saidsplit muzzle extension, and a plurality of inclined vane members carriedby said sleeve member laterally adjacent the mouth of saidsplit muzzleextension effective to rotate said sleeve member to constrict said splitmuzzle extension responsive to expansion of gases discharged from saidsplit muzzle extension. 3. Choke mechanism for a shotgun accordin toclaim 2 which comprises adjustable stop means adapted to arrest rotationof said sleeve member relative to said split muzzle extension.

4. The combination with a gun choke mechanism comprising a split muzzleextension and an annular member constructed and arranged to constrictthe former when rotated.'oi an annular projection of said annular memberextending beyond the mouth 01 said split muzzle tension, said projectionhavinga plurality of deflecting surfaces therein arranged to deflectexpanding gas discharged from said split muzzle extension to impartrotational torque eflective-to constrict said split muzzle extension.

5. The combination according to claim 4 comprising a detent adapted tobe selectively fixed in any one oi a plurality of angular positionsrelative to said split muzzle extension and a lug carried by saidannular member, the Iormer in the path of .the latter for arrestingrotation of said annular member at a predetermined angular positionrelative to said extension.

6. The combination with a gun choke mechani'sm comprising asplit muzzleextension and an annular member internally threaded for rotationrelative to said extension in threaded engagement therewith andconstructed and arranged to constrict said extension when rotated, oimeans rigidly carried by said annular member arranged to be rotated inthe presence of expanding gas discharged from said split muzzleextension, said means comprising an annular projection of said annularmember extending beyond the mouth of said split muzzle extension thathas its forward end constricted to a diameter approximately equal to butslightly larger than that of said split muzzle extension when the latteris not constricted, and that has in the wall thereof a plurality ofopenings through which expanding gas may pass, said openings'beirig soshaped as to deflect the path of expanding gas passing therethrough toimpart rotational ,torque to said annular projection.

'7. The combination of claim 6 wherein said annular projection has aplurality of longitudinally extending orifices surrounding theconstricted forward end thereof through which orifices expanding gas maypass for the purpose of imposing recoil directly on said annularprojection.

8. The combination with a gun choke mecha-' nism comprising anexternally tapered split muzzle extension and an internally taperedannular member internally threaded for rotation relative to saidextension in threaded engagement therewith and constructed and arrangedto constrict said extension when rotated, of a cylindrical chambermember rotatable integrally with said annular member having its internaldiameter larger than the internal diameter of said split muzzleextension when unconstricted and having its forward end constricted toprovide a bore of substantial length coaxial with said split muzzleextension and of internal diameter approximately equal to but slightlylarger than that of the split muzzle extension when unccnstrlcted, saidcylindrical chamber member being provided with a plurality of slotspresenting longitudinally extending deflecting surfaces for deflectingexpanding gas to impart rotational movement to said cylindrical chambermember for constricting said split muzzle extension.

9. The combination according to claim 8 where- I in said cylindricalchamber member has a plurality oi longitudinally extending orificessurrounding the constricted forward end of said chamber member whoseaxes are inclined to the axis oi said chamber member at an angle suchthat expanding gas passing therethrough imparts torque for impartingrotational movement to said chamber member in the same direction as thateii'ected by said deflecting surfaces provided by said slots and alsoimposes recoil directly on said said gun barrel and the internaldiameter of which provides proximate clearance for the widest shotpattern passing therethrough, said cylindri- 1 cal member havingopenings in the side well thereof arranged to deflect gas escapingtherethrough from said gun barrel after the firing of a shell withinsaid barrel so as to rotate said cylindrical member and said cam andthereby constrict said split muzzle extension.

11. The combination with a shotgun having a 'barrelwith an externallytapered constrictable split muzzle, of a sleeve threaded'on said muzzleand internally tapered to constrict said muzzle when rotated, saidsleeve extending beyond said muzzle to provide an expanded chamberhaving an orifice which is coaxial with said gun barrel and the internaldiameter of which provides proximate clearance for the widest shotpattern passing therethrough, said sleeve having openings in the wallthereof arranged to deflect gas escaping therethrough from said gunbarrel following the firing of a shell within said barrel for thepurpose of effecting a rotary motion in said sleeve to constrict saidsplit muzzle. I

12. Choke mechanism for a shotgun comprising a constrictablesplit-muzzle extension, an exit tube spaced from the mouth of said splitmuzzle extension in line therewith whose internal diameter providesproximate clearance for the shot pattern when the split muzzle extensionis not constricted, a rotatable vane carrying member laterally aperturedto provide vanes between the mouth of said split muzzle extension andsaid exit tube that are laterally adjacent the mouth of said muzzleextension and that are adapted to deflect expanding gases dischargedfrom said split muzzle extension to impart rotational torque to saidvane carrying member, and means for constricting said split muzzleextension responsive to rotation of said vane carrying member upondischarge of expanding gases from the mouth of said split muzzleextension.

13. Choke mechanism for a shotgun according to. claim 12 wherein saidvane carrying member has a side wall of annular cross-section that iscoaxial with said exit tube and is of larger internal diameter than saidexit tube immediately adjacent the inner end of said exit tube forproviding an obstruction of gases discharged from said split muzzleextension, the vanes carried by said -vane carrying member beingprovided by a plurality of longitudinally extending slots in said sidewall of said annular member inclined substantially in a common directionfrom radii extending from the axis of said vane carrying member.

14. A shotgun choke mechanism comprising a constrictable gun muzzleextension, a rotatable member cooperating with said constrictable gunmuzzle extension and constructed and arranged for constricting said gunmuzzle extension upon rotation of said member relative to said gunmuzzle'extension. and an extension carried by said member and havingexhaust vents presenting laterally inclined deflecting surfaces adjacentthe mouth of said constrictable gun muzzle extension and so directed asto produce rotation of said member to choke said gun muzzle extension inresponse to passage of the expanding explosion gases discharged fromsaid gun muzzle extension therethrough.

. JAMES E. 'A. EGLESON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 811,595 Taylor Feb. 6, 19062,398,298 Finlay et a1 Apr. 9, 1946

